What recruiters know about you is about to get a whole lot deeper than what you put on your resume. An emerging class of search engines is taking a big data approach to recruiting by crawling the Web for every bit of data about you, assembling it into a master profile, rating your knowledge, skill levels and interests, and serving it up to recruiters who can filter it by location, skill, the school you attended and a range of other criteria.

Today the technology is mainly used as a tool for finding scarce software development talent. But that could broaden into more types of jobs, including high-tech, legal, medical and engineering, according to the vendors and an analyst. (Read about some of the privacy implications of this technology.)

What Gild's algorithms tell recruiters about you

Here are two examples of Gild's algorithms for evaluating skills and knowledge based on what the company finds out about a subject on the Web. The company has created more than 50,000 of these "features," or rules, for its Gild Source service.

Using Bayesian analysis, Gild claims it can predict how skilled a subject might be even little data is available, such as when a person has no open-source code available for evaluation.

Raw data: In an online profile you describe yourself as proficient in C/C++.

Conclusion: You're not very good at either.

Logic: C and C++ are completely different languages. So why would you lump them together? Listing them together indicates that you may have just put them in as checklist items.

Raw data: On Twitter you recently said that Celery sucks.

Conclusion: You have knowledge of Python, Django and Celery.

Logic: The fact that you dislike the asynchronous processing toolkit, written in Python and used extensively in Python Web development, means you're not only familiar with Celery but almost certainly are knowledgeable about Python and Django, with which Celery is commonly used.

Last year Red Hat hired more than 1,000 people. But it wasn't easy to find the software development and engineering talent needed to fill many of those seats. "We use LinkedIn Recruiter extensively," says CIO Lee Congdon.

But the top-notch talent that the open-source software developer is looking for doesn't always bother keeping an updated resume on LinkedIn or elsewhere, and many of the best software engineers don't need to look on job boards for a better position.

So this year, Red Hat decided to be more proactive. It began using a cloud-based service from Gild that takes a big data approach, mining the social Web to identify and evaluate qualified talent.

Working with Gild, Red Hat was able to quickly come up with a ranked list of prospective software engineering candidates, complete with contact information that in some cases Gild harvests from the prospect's source code. "We're very satisfied with the early results," Congdon says.

Gild says it differentiates its offering by focusing on software developers and by downloading and evaluating code each subject has uploaded to development sites. Each subject receives an overall score as well as an influence score and years of experience for each skill. (This profile is not of a real person seeking a job.)